Ordering 33-year-old Carla Thompson to spend half her sentence in jail and the other half on supervised licence, Belfast Crown Court Judge David McFarland said that despite her clear record and other matters of mitigation, it was "fit and proper" that she went to jail.

"Premises like this are very vulnerable and for that reason the courts will always impose deterrent sentences so that you and people like you will not be tempted to treat these types of shops as easy targets," said the Recorder of Belfast.

Earlier he heard how a masked Thompson walked into the Boots pharmacy on the Upper Newtownards Road in east Belfast on July 28 last year and after "slashing" the air with a 7-inch kitchen knife, made off with a number of boxes of codeine painkillers.

Prosecution lawyer Kate McKay told the court that on the way out she threatened staff not to follow her, but despite her threats the pharmacist and a passer-by did follow her.

They stopped after she pulled a gun from the waist band of her tracksuit bottoms and pointed it at them.

A passer-by saw her getting into her own car and, having noted down the registration, called the police who were waiting outside Thompson's home at Victoria Drive in the Sydenham area.

Even as she was being arrested Thomspon told police "it was me who did it", and during later police interviews made "full and frank admissions" before pleading guilty to possessing the knife and committing the robbery.

Defence lawyer Martin Morgan told the court that Thomspon had been "in the grip" of an addiction to codeine-based painkillers for around 10 years.

He said that the addiction had led directly to her carrying out the robbery at the chemist's in what he said was "an act of desperation".